Enclosures for the intensive production of plants, particularly from seeds, these enclosures being called: frames, small glasshouses, transparent or translucent glass or plastics greenhouse are already known and widely used for cultivations of plant seedlings, flowers or similar. Such enclosures provide a protection of the vegetables against frost since the enclosures maintain a tepid and moist ambience favourable for the vegetable germination, growth or cultivation, and even for the breeding of small animals. However such enclosures, although they have given rather good results, require a lengthy and delicate work which has to be carried out right in time. Moreover, such enclosures withstand badly brutal spells of bad weather such as storms, heavy snow falls or hard frosts. Moreover, it is necessary on the one hand to provide various complicated and costly means for a periodical watering highly supervised in quality and quantity, and on the other hand to sometimes complete by a heat supply the temperature prevailing inside such enclosures.
The present invention remedies these disadvantages by providing closed enclosures the upper portion or cover of which has a shape such that there is provided a very simple setting of its operation, thereby greatly reducing the work to be done and the maintenance costs.